The present invention relates to systems for producing fluid from hydrocarbon formations, and more specifically is directed to methods and apparatus for producing fluids from a plurality of producing formations intersected by a well.
It is well known that wellbores drilled for the production of hydrocarbons often pass through two or more producing formations. Fluids from the producing formations typically enter the well through perforations formed in a well casing adjacent the producing formation. Fluids contained in the formation may be raised by pumping systems to another zone or to collection points above the surface of the earth. There are a number of methods that have been developed for producing multiple zone wells. For example, one traditional method of producing a multiple zone well is to isolate the zones using packers or the like, and to produce the well one zone at a time from the bottom of the well upwardly until each zone is exhausted. Producing the well in this manner, however, may cause the well to fluctuate between production peaks and only marginal production as each zone is exhausted. Other methods for producing multiple formations in oil and gas wells are set forth in U.S. Pat. No. 6,250,390 B1 and U.S. Pat. No. 5,881,814. U.S. Pat. No. 5,881,814 discloses an apparatus for producing fluid from two producing zones through a single production tubing with progressive cavity pumps. U.S. Pat. No. 6,250,390 B1 discloses a dual submersible pumping system and permits the pumping of fluid from separate zones without commingling of fluids.
While there are a number of methods and apparatus for producing fluid from a wellbore with multiple producing formations, there is still a need for improved methods and apparatus of doing so. For example, in addition to preventing cross flow between reservoirs, it is sometimes desirable to determine the production from each zone. Thus there is a need for an apparatus that will produce from more than one zone to maximize production from the well, and that will provide for a method to determine the amount of production from each zone whether or not fluids from different zones are produced in the well separately or are commingled and produced upwardly in a single stream.
The present invention is directed to a method and apparatus for producing fluids from multiple formations intersected by a well. In one embodiment the present invention has a first packer, which is preferably a dual packer, positioned in the well above an uppermost producing formation. A second packer is positioned in the well to divide the well into upper and lower production zones. The first packer has first and second openings therein. Both the upper and lower production zones include at least one and may each have a plurality of producing formations.
A first flow conduit is received in an opening in the first, or upper packer and extends both above and below the dual packer so that fluid from the first production zone may be communicated through the first flow conduit upwardly in the well. The fluid from the first production zone may be discharged into an interior of the well above the first packer. A second flow conduit is received in an opening in the upper packer and extends downwardly therefrom into an opening in the second or lower packer. The second flow conduit will thus communicate fluid from the lower production zone into the well above the first packer. Fluid from the second production zone may be discharged into the interior of the well above the first packer. A pumping system is lowered into the well on a production tubing. The pumping system is located above the first packer and will communicate fluid from both the first and second production zones upwardly in the production tubing. Thus, fluid from the lower production zone and the upper production zone will be combined and produced upwardly in a single stream in the production tubing on which the pumping system is lowered. The pumping system is preferably an electric submersible pumping system and thus includes an electric submersible pump, driven by an electric motor.
Each of the first and second flow conduits preferably has a check valve positioned therein. The check valve will allow for flow upwardly through the flow conduits but will prevent the flow of fluid downward therethrough. A flow meter is connected in one of the first or second flow conduits for measuring the amount of fluid flow from the zone with which the flow meter is operably associated. Preferably, the flow meter is positioned in the first flow conduit above the check valve therein and thus will measure the rate of flow from the first or upper production zone. The amount of fluid produced from each zone can thus be determined, even though fluid from both the upper and lower production zones is delivered to the surface in a single stream. The amount of fluid produced from the first or upper production zone can be determined with the flow meter, and the amount of fluid produced from the lower zone can be determined simply by subtracting the amount of fluid produced from the upper zone from the total amount of output through the production tubing.
The first flow conduit may comprise a tailpipe connected to the lower end of the pumping system and extending downwardly therefrom into the opening in the dual packer. The tailpipe will comprise a perforated tailpipe and thus will have ports therethrough above the flow meter to allow fluid from the upper production zone to be discharged into the interior of the well and then to be passed into the intake for the pump and pumped upwardly in the production tubing. The present invention thus provides a method and apparatus for producing fluids from multiple formations in a well, and for determining the amount of fluid produced from each zone, whether the fluid is produced up the well in a single stream or in separate streams.